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  <h1>Source code for torchvision.io.video</h1><div class="highlight"><pre>
<span></span><span class="kn">import</span> <span class="nn">gc</span>
<span class="kn">import</span> <span class="nn">math</span>
<span class="kn">import</span> <span class="nn">re</span>
<span class="kn">import</span> <span class="nn">warnings</span>
<span class="kn">from</span> <span class="nn">typing</span> <span class="kn">import</span> <span class="n">Tuple</span><span class="p">,</span> <span class="n">List</span>

<span class="kn">import</span> <span class="nn">numpy</span> <span class="k">as</span> <span class="nn">np</span>
<span class="kn">import</span> <span class="nn">torch</span>

<span class="kn">from</span> <span class="nn">.</span> <span class="kn">import</span> <span class="n">_video_opt</span>
<span class="kn">from</span> <span class="nn">._video_opt</span> <span class="kn">import</span> <span class="n">VideoMetaData</span>


<span class="k">try</span><span class="p">:</span>
    <span class="kn">import</span> <span class="nn">av</span>

    <span class="n">av</span><span class="o">.</span><span class="n">logging</span><span class="o">.</span><span class="n">set_level</span><span class="p">(</span><span class="n">av</span><span class="o">.</span><span class="n">logging</span><span class="o">.</span><span class="n">ERROR</span><span class="p">)</span>
    <span class="k">if</span> <span class="ow">not</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">av</span><span class="o">.</span><span class="n">video</span><span class="o">.</span><span class="n">frame</span><span class="o">.</span><span class="n">VideoFrame</span><span class="p">,</span> <span class="s2">&quot;pict_type&quot;</span><span class="p">):</span>
        <span class="n">av</span> <span class="o">=</span> <span class="ne">ImportError</span><span class="p">(</span>
            <span class="sd">&quot;&quot;&quot;\</span>
<span class="sd">Your version of PyAV is too old for the necessary video operations in torchvision.</span>
<span class="sd">If you are on Python 3.5, you will have to build from source (the conda-forge</span>
<span class="sd">packages are not up-to-date).  See</span>
<span class="sd">https://github.com/mikeboers/PyAV#installation for instructions on how to</span>
<span class="sd">install PyAV on your system.</span>
<span class="sd">&quot;&quot;&quot;</span>
        <span class="p">)</span>
<span class="k">except</span> <span class="ne">ImportError</span><span class="p">:</span>
    <span class="n">av</span> <span class="o">=</span> <span class="ne">ImportError</span><span class="p">(</span>
        <span class="sd">&quot;&quot;&quot;\</span>
<span class="sd">PyAV is not installed, and is necessary for the video operations in torchvision.</span>
<span class="sd">See https://github.com/mikeboers/PyAV#installation for instructions on how to</span>
<span class="sd">install PyAV on your system.</span>
<span class="sd">&quot;&quot;&quot;</span>
    <span class="p">)</span>


<span class="k">def</span> <span class="nf">_check_av_available</span><span class="p">():</span>
    <span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">av</span><span class="p">,</span> <span class="ne">Exception</span><span class="p">):</span>
        <span class="k">raise</span> <span class="n">av</span>


<span class="k">def</span> <span class="nf">_av_available</span><span class="p">():</span>
    <span class="k">return</span> <span class="ow">not</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">av</span><span class="p">,</span> <span class="ne">Exception</span><span class="p">)</span>


<span class="c1"># PyAV has some reference cycles</span>
<span class="n">_CALLED_TIMES</span> <span class="o">=</span> <span class="mi">0</span>
<span class="n">_GC_COLLECTION_INTERVAL</span> <span class="o">=</span> <span class="mi">10</span>


<div class="viewcode-block" id="write_video"><a class="viewcode-back" href="../../../io.html#torchvision.io.write_video">[docs]</a><span class="k">def</span> <span class="nf">write_video</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">video_array</span><span class="p">,</span> <span class="n">fps</span><span class="p">,</span> <span class="n">video_codec</span><span class="o">=</span><span class="s2">&quot;libx264&quot;</span><span class="p">,</span> <span class="n">options</span><span class="o">=</span><span class="kc">None</span><span class="p">):</span>
    <span class="sd">&quot;&quot;&quot;</span>
<span class="sd">    Writes a 4d tensor in [T, H, W, C] format in a video file</span>

<span class="sd">    Parameters</span>
<span class="sd">    ----------</span>
<span class="sd">    filename : str</span>
<span class="sd">        path where the video will be saved</span>
<span class="sd">    video_array : Tensor[T, H, W, C]</span>
<span class="sd">        tensor containing the individual frames, as a uint8 tensor in [T, H, W, C] format</span>
<span class="sd">    fps : Number</span>
<span class="sd">        frames per second</span>
<span class="sd">    &quot;&quot;&quot;</span>
    <span class="n">_check_av_available</span><span class="p">()</span>
    <span class="n">video_array</span> <span class="o">=</span> <span class="n">torch</span><span class="o">.</span><span class="n">as_tensor</span><span class="p">(</span><span class="n">video_array</span><span class="p">,</span> <span class="n">dtype</span><span class="o">=</span><span class="n">torch</span><span class="o">.</span><span class="n">uint8</span><span class="p">)</span><span class="o">.</span><span class="n">numpy</span><span class="p">()</span>

    <span class="n">container</span> <span class="o">=</span> <span class="n">av</span><span class="o">.</span><span class="n">open</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">mode</span><span class="o">=</span><span class="s2">&quot;w&quot;</span><span class="p">)</span>

    <span class="n">stream</span> <span class="o">=</span> <span class="n">container</span><span class="o">.</span><span class="n">add_stream</span><span class="p">(</span><span class="n">video_codec</span><span class="p">,</span> <span class="n">rate</span><span class="o">=</span><span class="n">fps</span><span class="p">)</span>
    <span class="n">stream</span><span class="o">.</span><span class="n">width</span> <span class="o">=</span> <span class="n">video_array</span><span class="o">.</span><span class="n">shape</span><span class="p">[</span><span class="mi">2</span><span class="p">]</span>
    <span class="n">stream</span><span class="o">.</span><span class="n">height</span> <span class="o">=</span> <span class="n">video_array</span><span class="o">.</span><span class="n">shape</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span>
    <span class="n">stream</span><span class="o">.</span><span class="n">pix_fmt</span> <span class="o">=</span> <span class="s2">&quot;yuv420p&quot;</span> <span class="k">if</span> <span class="n">video_codec</span> <span class="o">!=</span> <span class="s2">&quot;libx264rgb&quot;</span> <span class="k">else</span> <span class="s2">&quot;rgb24&quot;</span>
    <span class="n">stream</span><span class="o">.</span><span class="n">options</span> <span class="o">=</span> <span class="n">options</span> <span class="ow">or</span> <span class="p">{}</span>

    <span class="k">for</span> <span class="n">img</span> <span class="ow">in</span> <span class="n">video_array</span><span class="p">:</span>
        <span class="n">frame</span> <span class="o">=</span> <span class="n">av</span><span class="o">.</span><span class="n">VideoFrame</span><span class="o">.</span><span class="n">from_ndarray</span><span class="p">(</span><span class="n">img</span><span class="p">,</span> <span class="nb">format</span><span class="o">=</span><span class="s2">&quot;rgb24&quot;</span><span class="p">)</span>
        <span class="n">frame</span><span class="o">.</span><span class="n">pict_type</span> <span class="o">=</span> <span class="s2">&quot;NONE&quot;</span>
        <span class="k">for</span> <span class="n">packet</span> <span class="ow">in</span> <span class="n">stream</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="n">frame</span><span class="p">):</span>
            <span class="n">container</span><span class="o">.</span><span class="n">mux</span><span class="p">(</span><span class="n">packet</span><span class="p">)</span>

    <span class="c1"># Flush stream</span>
    <span class="k">for</span> <span class="n">packet</span> <span class="ow">in</span> <span class="n">stream</span><span class="o">.</span><span class="n">encode</span><span class="p">():</span>
        <span class="n">container</span><span class="o">.</span><span class="n">mux</span><span class="p">(</span><span class="n">packet</span><span class="p">)</span>

    <span class="c1"># Close the file</span>
    <span class="n">container</span><span class="o">.</span><span class="n">close</span><span class="p">()</span></div>


<span class="k">def</span> <span class="nf">_read_from_stream</span><span class="p">(</span>
    <span class="n">container</span><span class="p">,</span> <span class="n">start_offset</span><span class="p">,</span> <span class="n">end_offset</span><span class="p">,</span> <span class="n">pts_unit</span><span class="p">,</span> <span class="n">stream</span><span class="p">,</span> <span class="n">stream_name</span>
<span class="p">):</span>
    <span class="k">global</span> <span class="n">_CALLED_TIMES</span><span class="p">,</span> <span class="n">_GC_COLLECTION_INTERVAL</span>
    <span class="n">_CALLED_TIMES</span> <span class="o">+=</span> <span class="mi">1</span>
    <span class="k">if</span> <span class="n">_CALLED_TIMES</span> <span class="o">%</span> <span class="n">_GC_COLLECTION_INTERVAL</span> <span class="o">==</span> <span class="n">_GC_COLLECTION_INTERVAL</span> <span class="o">-</span> <span class="mi">1</span><span class="p">:</span>
        <span class="n">gc</span><span class="o">.</span><span class="n">collect</span><span class="p">()</span>

    <span class="k">if</span> <span class="n">pts_unit</span> <span class="o">==</span> <span class="s2">&quot;sec&quot;</span><span class="p">:</span>
        <span class="n">start_offset</span> <span class="o">=</span> <span class="nb">int</span><span class="p">(</span><span class="n">math</span><span class="o">.</span><span class="n">floor</span><span class="p">(</span><span class="n">start_offset</span> <span class="o">*</span> <span class="p">(</span><span class="mi">1</span> <span class="o">/</span> <span class="n">stream</span><span class="o">.</span><span class="n">time_base</span><span class="p">)))</span>
        <span class="k">if</span> <span class="n">end_offset</span> <span class="o">!=</span> <span class="nb">float</span><span class="p">(</span><span class="s2">&quot;inf&quot;</span><span class="p">):</span>
            <span class="n">end_offset</span> <span class="o">=</span> <span class="nb">int</span><span class="p">(</span><span class="n">math</span><span class="o">.</span><span class="n">ceil</span><span class="p">(</span><span class="n">end_offset</span> <span class="o">*</span> <span class="p">(</span><span class="mi">1</span> <span class="o">/</span> <span class="n">stream</span><span class="o">.</span><span class="n">time_base</span><span class="p">)))</span>
    <span class="k">else</span><span class="p">:</span>
        <span class="n">warnings</span><span class="o">.</span><span class="n">warn</span><span class="p">(</span>
            <span class="s2">&quot;The pts_unit &#39;pts&#39; gives wrong results and will be removed in a &quot;</span>
            <span class="o">+</span> <span class="s2">&quot;follow-up version. Please use pts_unit &#39;sec&#39;.&quot;</span>
        <span class="p">)</span>

    <span class="n">frames</span> <span class="o">=</span> <span class="p">{}</span>
    <span class="n">should_buffer</span> <span class="o">=</span> <span class="kc">False</span>
    <span class="n">max_buffer_size</span> <span class="o">=</span> <span class="mi">5</span>
    <span class="k">if</span> <span class="n">stream</span><span class="o">.</span><span class="n">type</span> <span class="o">==</span> <span class="s2">&quot;video&quot;</span><span class="p">:</span>
        <span class="c1"># DivX-style packed B-frames can have out-of-order pts (2 frames in a single pkt)</span>
        <span class="c1"># so need to buffer some extra frames to sort everything</span>
        <span class="c1"># properly</span>
        <span class="n">extradata</span> <span class="o">=</span> <span class="n">stream</span><span class="o">.</span><span class="n">codec_context</span><span class="o">.</span><span class="n">extradata</span>
        <span class="c1"># overly complicated way of finding if `divx_packed` is set, following</span>
        <span class="c1"># https://github.com/FFmpeg/FFmpeg/commit/d5a21172283572af587b3d939eba0091484d3263</span>
        <span class="k">if</span> <span class="n">extradata</span> <span class="ow">and</span> <span class="sa">b</span><span class="s2">&quot;DivX&quot;</span> <span class="ow">in</span> <span class="n">extradata</span><span class="p">:</span>
            <span class="c1"># can&#39;t use regex directly because of some weird characters sometimes...</span>
            <span class="n">pos</span> <span class="o">=</span> <span class="n">extradata</span><span class="o">.</span><span class="n">find</span><span class="p">(</span><span class="sa">b</span><span class="s2">&quot;DivX&quot;</span><span class="p">)</span>
            <span class="n">d</span> <span class="o">=</span> <span class="n">extradata</span><span class="p">[</span><span class="n">pos</span><span class="p">:]</span>
            <span class="n">o</span> <span class="o">=</span> <span class="n">re</span><span class="o">.</span><span class="n">search</span><span class="p">(</span><span class="sa">br</span><span class="s2">&quot;DivX(\d+)Build(\d+)(\w)&quot;</span><span class="p">,</span> <span class="n">d</span><span class="p">)</span>
            <span class="k">if</span> <span class="n">o</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
                <span class="n">o</span> <span class="o">=</span> <span class="n">re</span><span class="o">.</span><span class="n">search</span><span class="p">(</span><span class="sa">br</span><span class="s2">&quot;DivX(\d+)b(\d+)(\w)&quot;</span><span class="p">,</span> <span class="n">d</span><span class="p">)</span>
            <span class="k">if</span> <span class="n">o</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
                <span class="n">should_buffer</span> <span class="o">=</span> <span class="n">o</span><span class="o">.</span><span class="n">group</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span> <span class="o">==</span> <span class="sa">b</span><span class="s2">&quot;p&quot;</span>
    <span class="n">seek_offset</span> <span class="o">=</span> <span class="n">start_offset</span>
    <span class="c1"># some files don&#39;t seek to the right location, so better be safe here</span>
    <span class="n">seek_offset</span> <span class="o">=</span> <span class="nb">max</span><span class="p">(</span><span class="n">seek_offset</span> <span class="o">-</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>
    <span class="k">if</span> <span class="n">should_buffer</span><span class="p">:</span>
        <span class="c1"># FIXME this is kind of a hack, but we will jump to the previous keyframe</span>
        <span class="c1"># so this will be safe</span>
        <span class="n">seek_offset</span> <span class="o">=</span> <span class="nb">max</span><span class="p">(</span><span class="n">seek_offset</span> <span class="o">-</span> <span class="n">max_buffer_size</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>
    <span class="k">try</span><span class="p">:</span>
        <span class="c1"># TODO check if stream needs to always be the video stream here or not</span>
        <span class="n">container</span><span class="o">.</span><span class="n">seek</span><span class="p">(</span><span class="n">seek_offset</span><span class="p">,</span> <span class="n">any_frame</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="n">backward</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">stream</span><span class="o">=</span><span class="n">stream</span><span class="p">)</span>
    <span class="k">except</span> <span class="n">av</span><span class="o">.</span><span class="n">AVError</span><span class="p">:</span>
        <span class="c1"># TODO add some warnings in this case</span>
        <span class="c1"># print(&quot;Corrupted file?&quot;, container.name)</span>
        <span class="k">return</span> <span class="p">[]</span>
    <span class="n">buffer_count</span> <span class="o">=</span> <span class="mi">0</span>
    <span class="k">try</span><span class="p">:</span>
        <span class="k">for</span> <span class="n">_idx</span><span class="p">,</span> <span class="n">frame</span> <span class="ow">in</span> <span class="nb">enumerate</span><span class="p">(</span><span class="n">container</span><span class="o">.</span><span class="n">decode</span><span class="p">(</span><span class="o">**</span><span class="n">stream_name</span><span class="p">)):</span>
            <span class="n">frames</span><span class="p">[</span><span class="n">frame</span><span class="o">.</span><span class="n">pts</span><span class="p">]</span> <span class="o">=</span> <span class="n">frame</span>
            <span class="k">if</span> <span class="n">frame</span><span class="o">.</span><span class="n">pts</span> <span class="o">&gt;=</span> <span class="n">end_offset</span><span class="p">:</span>
                <span class="k">if</span> <span class="n">should_buffer</span> <span class="ow">and</span> <span class="n">buffer_count</span> <span class="o">&lt;</span> <span class="n">max_buffer_size</span><span class="p">:</span>
                    <span class="n">buffer_count</span> <span class="o">+=</span> <span class="mi">1</span>
                    <span class="k">continue</span>
                <span class="k">break</span>
    <span class="k">except</span> <span class="n">av</span><span class="o">.</span><span class="n">AVError</span><span class="p">:</span>
        <span class="c1"># TODO add a warning</span>
        <span class="k">pass</span>
    <span class="c1"># ensure that the results are sorted wrt the pts</span>
    <span class="n">result</span> <span class="o">=</span> <span class="p">[</span>
        <span class="n">frames</span><span class="p">[</span><span class="n">i</span><span class="p">]</span> <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">sorted</span><span class="p">(</span><span class="n">frames</span><span class="p">)</span> <span class="k">if</span> <span class="n">start_offset</span> <span class="o">&lt;=</span> <span class="n">frames</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">.</span><span class="n">pts</span> <span class="o">&lt;=</span> <span class="n">end_offset</span>
    <span class="p">]</span>
    <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">frames</span><span class="p">)</span> <span class="o">&gt;</span> <span class="mi">0</span> <span class="ow">and</span> <span class="n">start_offset</span> <span class="o">&gt;</span> <span class="mi">0</span> <span class="ow">and</span> <span class="n">start_offset</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">frames</span><span class="p">:</span>
        <span class="c1"># if there is no frame that exactly matches the pts of start_offset</span>
        <span class="c1"># add the last frame smaller than start_offset, to guarantee that</span>
        <span class="c1"># we will have all the necessary data. This is most useful for audio</span>
        <span class="n">preceding_frames</span> <span class="o">=</span> <span class="p">[</span><span class="n">i</span> <span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="n">frames</span> <span class="k">if</span> <span class="n">i</span> <span class="o">&lt;</span> <span class="n">start_offset</span><span class="p">]</span>
        <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">preceding_frames</span><span class="p">)</span> <span class="o">&gt;</span> <span class="mi">0</span><span class="p">:</span>
            <span class="n">first_frame_pts</span> <span class="o">=</span> <span class="nb">max</span><span class="p">(</span><span class="n">preceding_frames</span><span class="p">)</span>
            <span class="n">result</span><span class="o">.</span><span class="n">insert</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="n">frames</span><span class="p">[</span><span class="n">first_frame_pts</span><span class="p">])</span>
    <span class="k">return</span> <span class="n">result</span>


<span class="k">def</span> <span class="nf">_align_audio_frames</span><span class="p">(</span><span class="n">aframes</span><span class="p">,</span> <span class="n">audio_frames</span><span class="p">,</span> <span class="n">ref_start</span><span class="p">,</span> <span class="n">ref_end</span><span class="p">):</span>
    <span class="n">start</span><span class="p">,</span> <span class="n">end</span> <span class="o">=</span> <span class="n">audio_frames</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">pts</span><span class="p">,</span> <span class="n">audio_frames</span><span class="p">[</span><span class="o">-</span><span class="mi">1</span><span class="p">]</span><span class="o">.</span><span class="n">pts</span>
    <span class="n">total_aframes</span> <span class="o">=</span> <span class="n">aframes</span><span class="o">.</span><span class="n">shape</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span>
    <span class="n">step_per_aframe</span> <span class="o">=</span> <span class="p">(</span><span class="n">end</span> <span class="o">-</span> <span class="n">start</span> <span class="o">+</span> <span class="mi">1</span><span class="p">)</span> <span class="o">/</span> <span class="n">total_aframes</span>
    <span class="n">s_idx</span> <span class="o">=</span> <span class="mi">0</span>
    <span class="n">e_idx</span> <span class="o">=</span> <span class="n">total_aframes</span>
    <span class="k">if</span> <span class="n">start</span> <span class="o">&lt;</span> <span class="n">ref_start</span><span class="p">:</span>
        <span class="n">s_idx</span> <span class="o">=</span> <span class="nb">int</span><span class="p">((</span><span class="n">ref_start</span> <span class="o">-</span> <span class="n">start</span><span class="p">)</span> <span class="o">/</span> <span class="n">step_per_aframe</span><span class="p">)</span>
    <span class="k">if</span> <span class="n">end</span> <span class="o">&gt;</span> <span class="n">ref_end</span><span class="p">:</span>
        <span class="n">e_idx</span> <span class="o">=</span> <span class="nb">int</span><span class="p">((</span><span class="n">ref_end</span> <span class="o">-</span> <span class="n">end</span><span class="p">)</span> <span class="o">/</span> <span class="n">step_per_aframe</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">aframes</span><span class="p">[:,</span> <span class="n">s_idx</span><span class="p">:</span><span class="n">e_idx</span><span class="p">]</span>


<div class="viewcode-block" id="read_video"><a class="viewcode-back" href="../../../io.html#torchvision.io.read_video">[docs]</a><span class="k">def</span> <span class="nf">read_video</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">start_pts</span><span class="o">=</span><span class="mi">0</span><span class="p">,</span> <span class="n">end_pts</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">pts_unit</span><span class="o">=</span><span class="s2">&quot;pts&quot;</span><span class="p">):</span>
    <span class="sd">&quot;&quot;&quot;</span>
<span class="sd">    Reads a video from a file, returning both the video frames as well as</span>
<span class="sd">    the audio frames</span>

<span class="sd">    Parameters</span>
<span class="sd">    ----------</span>
<span class="sd">    filename : str</span>
<span class="sd">        path to the video file</span>
<span class="sd">    start_pts : int if pts_unit = &#39;pts&#39;, optional</span>
<span class="sd">        float / Fraction if pts_unit = &#39;sec&#39;, optional</span>
<span class="sd">        the start presentation time of the video</span>
<span class="sd">    end_pts : int if pts_unit = &#39;pts&#39;, optional</span>
<span class="sd">        float / Fraction if pts_unit = &#39;sec&#39;, optional</span>
<span class="sd">        the end presentation time</span>
<span class="sd">    pts_unit : str, optional</span>
<span class="sd">        unit in which start_pts and end_pts values will be interpreted, either &#39;pts&#39; or &#39;sec&#39;. Defaults to &#39;pts&#39;.</span>

<span class="sd">    Returns</span>
<span class="sd">    -------</span>
<span class="sd">    vframes : Tensor[T, H, W, C]</span>
<span class="sd">        the `T` video frames</span>
<span class="sd">    aframes : Tensor[K, L]</span>
<span class="sd">        the audio frames, where `K` is the number of channels and `L` is the</span>
<span class="sd">        number of points</span>
<span class="sd">    info : Dict</span>
<span class="sd">        metadata for the video and audio. Can contain the fields video_fps (float)</span>
<span class="sd">        and audio_fps (int)</span>
<span class="sd">    &quot;&quot;&quot;</span>

    <span class="kn">from</span> <span class="nn">torchvision</span> <span class="kn">import</span> <span class="n">get_video_backend</span>

    <span class="k">if</span> <span class="n">get_video_backend</span><span class="p">()</span> <span class="o">!=</span> <span class="s2">&quot;pyav&quot;</span><span class="p">:</span>
        <span class="k">return</span> <span class="n">_video_opt</span><span class="o">.</span><span class="n">_read_video</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">start_pts</span><span class="p">,</span> <span class="n">end_pts</span><span class="p">,</span> <span class="n">pts_unit</span><span class="p">)</span>

    <span class="n">_check_av_available</span><span class="p">()</span>

    <span class="k">if</span> <span class="n">end_pts</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
        <span class="n">end_pts</span> <span class="o">=</span> <span class="nb">float</span><span class="p">(</span><span class="s2">&quot;inf&quot;</span><span class="p">)</span>

    <span class="k">if</span> <span class="n">end_pts</span> <span class="o">&lt;</span> <span class="n">start_pts</span><span class="p">:</span>
        <span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span>
            <span class="s2">&quot;end_pts should be larger than start_pts, got &quot;</span>
            <span class="s2">&quot;start_pts=</span><span class="si">{}</span><span class="s2"> and end_pts=</span><span class="si">{}</span><span class="s2">&quot;</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">start_pts</span><span class="p">,</span> <span class="n">end_pts</span><span class="p">)</span>
        <span class="p">)</span>

    <span class="n">info</span> <span class="o">=</span> <span class="p">{}</span>
    <span class="n">video_frames</span> <span class="o">=</span> <span class="p">[]</span>
    <span class="n">audio_frames</span> <span class="o">=</span> <span class="p">[]</span>

    <span class="k">try</span><span class="p">:</span>
        <span class="n">container</span> <span class="o">=</span> <span class="n">av</span><span class="o">.</span><span class="n">open</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">metadata_errors</span><span class="o">=</span><span class="s2">&quot;ignore&quot;</span><span class="p">)</span>
    <span class="k">except</span> <span class="n">av</span><span class="o">.</span><span class="n">AVError</span><span class="p">:</span>
        <span class="c1"># TODO raise a warning?</span>
        <span class="k">pass</span>
    <span class="k">else</span><span class="p">:</span>
        <span class="k">if</span> <span class="n">container</span><span class="o">.</span><span class="n">streams</span><span class="o">.</span><span class="n">video</span><span class="p">:</span>
            <span class="n">video_frames</span> <span class="o">=</span> <span class="n">_read_from_stream</span><span class="p">(</span>
                <span class="n">container</span><span class="p">,</span>
                <span class="n">start_pts</span><span class="p">,</span>
                <span class="n">end_pts</span><span class="p">,</span>
                <span class="n">pts_unit</span><span class="p">,</span>
                <span class="n">container</span><span class="o">.</span><span class="n">streams</span><span class="o">.</span><span class="n">video</span><span class="p">[</span><span class="mi">0</span><span class="p">],</span>
                <span class="p">{</span><span class="s2">&quot;video&quot;</span><span class="p">:</span> <span class="mi">0</span><span class="p">},</span>
            <span class="p">)</span>
            <span class="n">video_fps</span> <span class="o">=</span> <span class="n">container</span><span class="o">.</span><span class="n">streams</span><span class="o">.</span><span class="n">video</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">average_rate</span>
            <span class="c1"># guard against potentially corrupted files</span>
            <span class="k">if</span> <span class="n">video_fps</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
                <span class="n">info</span><span class="p">[</span><span class="s2">&quot;video_fps&quot;</span><span class="p">]</span> <span class="o">=</span> <span class="nb">float</span><span class="p">(</span><span class="n">video_fps</span><span class="p">)</span>

        <span class="k">if</span> <span class="n">container</span><span class="o">.</span><span class="n">streams</span><span class="o">.</span><span class="n">audio</span><span class="p">:</span>
            <span class="n">audio_frames</span> <span class="o">=</span> <span class="n">_read_from_stream</span><span class="p">(</span>
                <span class="n">container</span><span class="p">,</span>
                <span class="n">start_pts</span><span class="p">,</span>
                <span class="n">end_pts</span><span class="p">,</span>
                <span class="n">pts_unit</span><span class="p">,</span>
                <span class="n">container</span><span class="o">.</span><span class="n">streams</span><span class="o">.</span><span class="n">audio</span><span class="p">[</span><span class="mi">0</span><span class="p">],</span>
                <span class="p">{</span><span class="s2">&quot;audio&quot;</span><span class="p">:</span> <span class="mi">0</span><span class="p">},</span>
            <span class="p">)</span>
            <span class="n">info</span><span class="p">[</span><span class="s2">&quot;audio_fps&quot;</span><span class="p">]</span> <span class="o">=</span> <span class="n">container</span><span class="o">.</span><span class="n">streams</span><span class="o">.</span><span class="n">audio</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">rate</span>

        <span class="n">container</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>

    <span class="n">vframes</span> <span class="o">=</span> <span class="p">[</span><span class="n">frame</span><span class="o">.</span><span class="n">to_rgb</span><span class="p">()</span><span class="o">.</span><span class="n">to_ndarray</span><span class="p">()</span> <span class="k">for</span> <span class="n">frame</span> <span class="ow">in</span> <span class="n">video_frames</span><span class="p">]</span>
    <span class="n">aframes</span> <span class="o">=</span> <span class="p">[</span><span class="n">frame</span><span class="o">.</span><span class="n">to_ndarray</span><span class="p">()</span> <span class="k">for</span> <span class="n">frame</span> <span class="ow">in</span> <span class="n">audio_frames</span><span class="p">]</span>

    <span class="k">if</span> <span class="n">vframes</span><span class="p">:</span>
        <span class="n">vframes</span> <span class="o">=</span> <span class="n">torch</span><span class="o">.</span><span class="n">as_tensor</span><span class="p">(</span><span class="n">np</span><span class="o">.</span><span class="n">stack</span><span class="p">(</span><span class="n">vframes</span><span class="p">))</span>
    <span class="k">else</span><span class="p">:</span>
        <span class="n">vframes</span> <span class="o">=</span> <span class="n">torch</span><span class="o">.</span><span class="n">empty</span><span class="p">((</span><span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">3</span><span class="p">),</span> <span class="n">dtype</span><span class="o">=</span><span class="n">torch</span><span class="o">.</span><span class="n">uint8</span><span class="p">)</span>

    <span class="k">if</span> <span class="n">aframes</span><span class="p">:</span>
        <span class="n">aframes</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">concatenate</span><span class="p">(</span><span class="n">aframes</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
        <span class="n">aframes</span> <span class="o">=</span> <span class="n">torch</span><span class="o">.</span><span class="n">as_tensor</span><span class="p">(</span><span class="n">aframes</span><span class="p">)</span>
        <span class="n">aframes</span> <span class="o">=</span> <span class="n">_align_audio_frames</span><span class="p">(</span><span class="n">aframes</span><span class="p">,</span> <span class="n">audio_frames</span><span class="p">,</span> <span class="n">start_pts</span><span class="p">,</span> <span class="n">end_pts</span><span class="p">)</span>
    <span class="k">else</span><span class="p">:</span>
        <span class="n">aframes</span> <span class="o">=</span> <span class="n">torch</span><span class="o">.</span><span class="n">empty</span><span class="p">((</span><span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">),</span> <span class="n">dtype</span><span class="o">=</span><span class="n">torch</span><span class="o">.</span><span class="n">float32</span><span class="p">)</span>

    <span class="k">return</span> <span class="n">vframes</span><span class="p">,</span> <span class="n">aframes</span><span class="p">,</span> <span class="n">info</span></div>


<span class="k">def</span> <span class="nf">_can_read_timestamps_from_packets</span><span class="p">(</span><span class="n">container</span><span class="p">):</span>
    <span class="n">extradata</span> <span class="o">=</span> <span class="n">container</span><span class="o">.</span><span class="n">streams</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="o">.</span><span class="n">codec_context</span><span class="o">.</span><span class="n">extradata</span>
    <span class="k">if</span> <span class="n">extradata</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
        <span class="k">return</span> <span class="kc">False</span>
    <span class="k">if</span> <span class="sa">b</span><span class="s2">&quot;Lavc&quot;</span> <span class="ow">in</span> <span class="n">extradata</span><span class="p">:</span>
        <span class="k">return</span> <span class="kc">True</span>
    <span class="k">return</span> <span class="kc">False</span>


<div class="viewcode-block" id="read_video_timestamps"><a class="viewcode-back" href="../../../io.html#torchvision.io.read_video_timestamps">[docs]</a><span class="k">def</span> <span class="nf">read_video_timestamps</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">pts_unit</span><span class="o">=</span><span class="s2">&quot;pts&quot;</span><span class="p">):</span>
    <span class="sd">&quot;&quot;&quot;</span>
<span class="sd">    List the video frames timestamps.</span>

<span class="sd">    Note that the function decodes the whole video frame-by-frame.</span>

<span class="sd">    Parameters</span>
<span class="sd">    ----------</span>
<span class="sd">    filename : str</span>
<span class="sd">        path to the video file</span>
<span class="sd">    pts_unit : str, optional</span>
<span class="sd">        unit in which timestamp values will be returned either &#39;pts&#39; or &#39;sec&#39;. Defaults to &#39;pts&#39;.</span>

<span class="sd">    Returns</span>
<span class="sd">    -------</span>
<span class="sd">    pts : List[int] if pts_unit = &#39;pts&#39;</span>
<span class="sd">        List[Fraction] if pts_unit = &#39;sec&#39;</span>
<span class="sd">        presentation timestamps for each one of the frames in the video.</span>
<span class="sd">    video_fps : int</span>
<span class="sd">        the frame rate for the video</span>

<span class="sd">    &quot;&quot;&quot;</span>
    <span class="kn">from</span> <span class="nn">torchvision</span> <span class="kn">import</span> <span class="n">get_video_backend</span>

    <span class="k">if</span> <span class="n">get_video_backend</span><span class="p">()</span> <span class="o">!=</span> <span class="s2">&quot;pyav&quot;</span><span class="p">:</span>
        <span class="k">return</span> <span class="n">_video_opt</span><span class="o">.</span><span class="n">_read_video_timestamps</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">pts_unit</span><span class="p">)</span>

    <span class="n">_check_av_available</span><span class="p">()</span>

    <span class="n">video_frames</span> <span class="o">=</span> <span class="p">[]</span>
    <span class="n">video_fps</span> <span class="o">=</span> <span class="kc">None</span>

    <span class="k">try</span><span class="p">:</span>
        <span class="n">container</span> <span class="o">=</span> <span class="n">av</span><span class="o">.</span><span class="n">open</span><span class="p">(</span><span class="n">filename</span><span class="p">,</span> <span class="n">metadata_errors</span><span class="o">=</span><span class="s2">&quot;ignore&quot;</span><span class="p">)</span>
    <span class="k">except</span> <span class="n">av</span><span class="o">.</span><span class="n">AVError</span><span class="p">:</span>
        <span class="c1"># TODO add a warning</span>
        <span class="k">pass</span>
    <span class="k">else</span><span class="p">:</span>
        <span class="k">if</span> <span class="n">container</span><span class="o">.</span><span class="n">streams</span><span class="o">.</span><span class="n">video</span><span class="p">:</span>
            <span class="n">video_stream</span> <span class="o">=</span> <span class="n">container</span><span class="o">.</span><span class="n">streams</span><span class="o">.</span><span class="n">video</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>
            <span class="n">video_time_base</span> <span class="o">=</span> <span class="n">video_stream</span><span class="o">.</span><span class="n">time_base</span>
            <span class="k">if</span> <span class="n">_can_read_timestamps_from_packets</span><span class="p">(</span><span class="n">container</span><span class="p">):</span>
                <span class="c1"># fast path</span>
                <span class="n">video_frames</span> <span class="o">=</span> <span class="p">[</span>
                    <span class="n">x</span> <span class="k">for</span> <span class="n">x</span> <span class="ow">in</span> <span class="n">container</span><span class="o">.</span><span class="n">demux</span><span class="p">(</span><span class="n">video</span><span class="o">=</span><span class="mi">0</span><span class="p">)</span> <span class="k">if</span> <span class="n">x</span><span class="o">.</span><span class="n">pts</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span>
                <span class="p">]</span>
            <span class="k">else</span><span class="p">:</span>
                <span class="n">video_frames</span> <span class="o">=</span> <span class="n">_read_from_stream</span><span class="p">(</span>
                    <span class="n">container</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="nb">float</span><span class="p">(</span><span class="s2">&quot;inf&quot;</span><span class="p">),</span> <span class="n">pts_unit</span><span class="p">,</span> <span class="n">video_stream</span><span class="p">,</span> <span class="p">{</span><span class="s2">&quot;video&quot;</span><span class="p">:</span> <span class="mi">0</span><span class="p">}</span>
                <span class="p">)</span>
            <span class="n">video_fps</span> <span class="o">=</span> <span class="nb">float</span><span class="p">(</span><span class="n">video_stream</span><span class="o">.</span><span class="n">average_rate</span><span class="p">)</span>
        <span class="n">container</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>

    <span class="n">pts</span> <span class="o">=</span> <span class="p">[</span><span class="n">x</span><span class="o">.</span><span class="n">pts</span> <span class="k">for</span> <span class="n">x</span> <span class="ow">in</span> <span class="n">video_frames</span><span class="p">]</span>

    <span class="k">if</span> <span class="n">pts_unit</span> <span class="o">==</span> <span class="s2">&quot;sec&quot;</span><span class="p">:</span>
        <span class="n">pts</span> <span class="o">=</span> <span class="p">[</span><span class="n">x</span> <span class="o">*</span> <span class="n">video_time_base</span> <span class="k">for</span> <span class="n">x</span> <span class="ow">in</span> <span class="n">pts</span><span class="p">]</span>

    <span class="k">return</span> <span class="n">pts</span><span class="p">,</span> <span class="n">video_fps</span></div>
</pre></div>

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